Move all keyring functions to one place and separate LUKS2 specific
code to generic handling.
Also fix possible mismatch if volume key is in keyring but it is not native
LUKS2 device (libarary cannot process such a device properly).
This fixes crypt_keyslot_add_by_key where we were unable to store
keyslot (unbound to segment) with different key_size.
The code used (new) volume key size implicitly which could be wrong
if new size was not compatible with cipher parameter for keyslot area.
Reduce bloated code in low level keyring utilities code.
Move log messages higher the library code.
Also return -ENOTSUP when code was compiled out by configure
option.
Remove code for handling multiple digests per single keyslot.
Same would apply to segments with the only exception of segment
in-reencryption. We need that exception so that we will not lose
old key digests too early.
Originally the key description for VK was derived
from segment id. This could lead to ambiguity when
keyslot key is verified and loaded in kernel keyring
using activation functions with CRYPT_ACTIVATE_KEYRING_KEY
flag raised.
before this patch any LUKS2 requirement defined in header
would stop a restricted operation from proceeding further.
This patch adds ability to mask requirements (internal only).
